What do the state features of KukaGymEnv represent?
Here's an incomplete answer, but it may help.
Your state is read by the function getExtendedObservation(). This function makes two things : it calls the function getObservation() from this source code, gets a state, and extend this state with three components :

relative x,y position and euler angle of block in gripper space

But what are the 5 first components returned by getObservation()? From what I read, there are positions, then euler angles describing the orientation. But that would make 6 + 3 = 9 features, so there is either only 2 positions, or only 2 euler angles. You may know kuka better than me and know the answer of this one :).
So, to sum up :
state = [X, Y, (Z, ) , Alpha, Gamma, (Beta, ), gripX, gripY, gripAlpha]

(Either Z or Beta is absent)